Most combined fluid and electrical hoses have the wires built into the wall of the hose in a straight, spiralled or braided fashion. These wires are placed around or along the outside surface of the inner hose before the outer jacket is moulded into place or they are embedded in one of the hose layers.
U.S. Pat. No. 3,457,359 to Soucy discloses one such hose having a wire braid reinforcing layer which acts as a grounding conductor to dissipate electric charge which may build up in the hose. U.S. Pat. No. 4,675,780 to Barnes also discloses a reinforced integral layer of conductive fiber bundles.
U.S. Pat. No. 3,899,631 to Clark discloses an inflatable tube having electrical conductors which are integrally formed in the elastomer outer cover of the inflatable tube.
These hoses are special application products made at greater expense than a normal fluid or air hose and which after manufacture is converted to add the electrical connection capability. Typically the production of special application hoses involves extensive development costs and large start-up production quantities for each version.
In use, when initially pressurised, a combined air or fluid and electrical hose contracts. It also stretches beyond its original length when subjected to lengthwise tension. The embedded wire, subjected to compressive and tensile forces, kinks and stretches out. Repetition of the stretching and kinking of the wire causes the wire to fail and break two to three inches from the terminations after a very short period of time, even during normal usage.
In the present invention, the electrical wire extends longitudinally and freely the full length of the hose without attachment to the inner hose wall. Further, the present invention provides a strength member which may be incorporated into the bore of the hose to limit stretch of the hose.